1. Field of the Invention
The present invention generally relates to a board lock for securing an electrical device, such as a connector, to a substrate, and in particular to a universal board lock which is capable of securing an electrical device to substrates of different thicknesses.
2. The Prior Art
An electrical circuit usually comprises a printed circuit board on which a plurality of electrical elements and devices are mounted. Some of the electrical elements are fixed to the circuit board by means of external fasteners or board locks before being soldered to the circuit board. Examples of board locks are shown in Taiwan Patent Application Nos. 83112290 and 84101384.
The conventional board locks comprise a plate-like base from which two resilient legs extend. The legs have barbs formed on free ends thereof opposite each other whereby when the legs are inserted into a hole defined in a substrate, the barbs extend beyond a bottom surface of the substrate and engage therewith.
FIG. 1A of the attached drawings shows a conventional board lock 50. The board lock 50 comprises an enlarged plate-like base section 51 from which two resilient legs 52 extend. Each resilient leg 52 has a barb 53 formed on a free end thereof. The board lock 50 is received in a bore 71 defined in an electrical device 70, such as a connector, whereby the base section 51 is supported on a shoulder 72 of the device 70 and the legs 52 extend through a narrow section of the bore 71.
The legs 52 are received in a hole 61 defined in a circuit board 60. The free ends of the legs 52 extend through the hole 61 and the barbs 53 engage with a bottom surface of the circuit board 60 thereby securing the electrical connector 70 to the circuit board 60.
The securement of the electrical connector 70 to the circuit board 60 is basically provided by the engagement between the barbs 53 and the bottom surface of the circuit board 60. This implies that the axial dimension of the legs 52 has to substantially correspond to the thickness of the circuit board 60 in order to ensure an effective securement of the electrical connector 70 to the circuit board 60.
As shown in FIG. 1B, if the legs 52 have a length substantially greater than the thickness of a circuit board 60' and extend through a hole 61' defined in the circuit board 60', then a distance exists between the barbs 53 and the bottom surface of the circuit board 60'. This distance prevents the barbs 53 from securely engaging with the bottom surface of the circuit board 60' and the connector 70 is not soundly secured on the circuit board 60'.
Therefore, a disadvantage associated with such a conventional design is that different board locks must be used for circuit boards having different thicknesses.
It is thus desirable to have a universal board lock which allows an electrical device to be effectively secured to substrates of different thicknesses.